Effect of thermosonication on peroxides enzyme activity and color parameters of carrot juice

In this study carrot juice samples were sonicated according to a D-optimal design response surface with different treatment of sonication temperature (25, 37.5 and 500C), sonication time (10, 20 and 30 min) and sonication power (350, 400w) at a constant frequency of 24 kHz. The results showed that ultrasound temperature (P<0.01), time (P<0.01) and interaction between time and temperature (P<0.01) significantly decreased the peroxidase enzyme activity of carrot juice samples and a prediction model obtained with high coefficients determination (R2 98%). Enzyme activity thermal treated juice processed at 90-880C for 4 min was undetectable. Ultrasound time significantly decreased the L-value, a-value, b-value, and TCD Blank (P< 0.05) of carrot juice samples. Whereas ultrasound temperature significantly increased the a value (P<0.01) and TCD Blank (P<0.05) samples. The obtained results showed that, ultrasound treatment significantly decreased peroxidase enzyme activity due to cavitational effects and reduced color parameters degradation specially a-value of carrot juice. Thus in order to maintain the quality of processed carrot juice; ultrasound processing could be accompanied by additional measures such as exclusion of oxygen, refrigerated storage and the use of natural enzyme inhibitors.